On the Doppler Effect and Church...

I saw an interesting display of the Doppler Effect in church service today. Well... I guess I should say that I saw and heard an interesting display of the Doppler Effect. We have a group of ladies that perform in a hand bell chorus every so often. Today we heard two songs and before the second song the choir director alerted us to look and hear for the innovative way in which the bells were used. At one point in the song several of the ladies rang their bells and then, as the bells were still vibrating, they quickly moved the bells backward and then just as quickly moved them forward. The resulting tonal shift was, indeed, very innovative and pleasant.